A novel approach to the generation of human monoclonal antibodies will be investigated. C.B-17scid/scid (SCID) mice will be engrafted with human peripheral blood lymphocytes (PBL). These animals will be immunized with a variety of antigens, in order to provoke an immune response by the human PBL. Antigens to be tested include: sheep red blood cells, dextran, keyhole limpet hemacyanin (KLH) as a model protein antigen, the haptens dinitrophenol and phthalate conjugated to KLH, and the human lung tumor cell line A549. Human PBL populating the spleen of immunized animals will be fused with the murine plasmacytoma cell line P3X63.Ag8.653 using PEG, and the resultant hybridomas selected in HAT-containing medium. The growth medium from hybridomacultures will be screened for the presence of antibodies specific for the immunogen. Positive cultures will be cloned by limiting dilution and retested for anti ' body production. The human origin of these monoclonal antibodies will be verified and their isotype determined by ELISA. It is anticipated that this novel approach to the generation of human monoclonal antibodies will allow the production of monoclonal antibodies against a vast array of antigens of relevance in the research and clonical laboratory and will allow new diagnostic and therapeutic applications.